In the electronic industry, an important factor is the rapid and accurate assembly of leads, terminals and contacts with the contact pads of printed circuit boards or other substrates. For convenience of connecting such elements, it has previously been suggested to facilitate the soldering of their connection by securing a solder slug or mass to one of the elements so that, when positioned in engagement with the other element and heated, the molten solder will cover the adjacent surfaces of both elements to form, when cooled, a soldered joint providing both a mechanical coupling and an electrical connection between the elements. Various arrangements of solder-holding elements are disclosed in Seidler U.S. Pat. Nos. 4,120,558, 4,203,648, 4,679,889 and 5,052,954 in each of which a lead has a finger or tab struck from it holding a solder mass to the lead.
As the art has progressed, there has been an increasing need for connectors between various types of devices, such as recent developments in "smart cards" which generally include a credit-card-sized substrate including integrated circuit elements which can be repeatedly reprogrammed to alter the stored information on the card. These integrated circuits are connected to terminals (i.e., contact pads) on the faces or edges of the smart card. Many uses have been suggested for these smart cards, including bank cards that include not only account identification information, but also current balance information or the like.
There is therefore a need for easily connecting a smart card or the like having exposed contact pads, to other circuit elements which would be responsible for reading and recording or otherwise processing the information stored on the card. One type of connector that could be adapted for use with a smart card is the edge clip connector shown in FIG. 10 of Seidler U.S. Pat. Nos. 4,679,889, 4,728,305 which shows a device for permitting connecting a plug-in printed circuit board to another substrate by surface mounting. This connection includes a multiple-contact circuit board edge connector having a housing in which are mounted spring contacts for separable connection to contact pads on a circuit board when inserted. Extending from the bottom of the housing and integral with the individual spring contacts are leads which are bent outwardly at a right angle from the spring contacts so that the connector may be surface mounted to a substrate that is in a perpendicular relationship with the circuit board. The terminal end of each spring contact is formed to carry a solid solder mass, which is placed in register with a respective contact pad of the substrate and soldered to it by usual IR or vapor soldering techniques. Alternatively, the solder mass was omitted, and paste solder and flux applied to the contact pads before aligning the connector terminal ends.
There are significant drawbacks to this configuration, however. First, not all components are intended to be surface mounted, and in certain space configurations, surface mounting would be impossible. Second, since the two solder-bearing terminals of the connector are both contacting the same surface of the substrate and are essentially resting on the substrate, it is necessary to accurately hold the leads with respect to the contact pads on the substrate during soldering to prevent improper soldered connections.